1. Field of the Invention
The present invention relates to a method of manufacturing an electronic device and more particularly to a method of manufacturing an electronic device equipped with a semiconductor integrated circuit, including IC cards, valuable papers, contactless identification devices and the like.
2. Description of the Prior Art
Recently, some electronic devices are estimated to have a promised potential that these devices, including IC cards equipped with an IC chip, a tag, and an identification devices by radio frequency technology, may incorporate a functionality in addition to the recognition of bar codes of the prior technology.
Now an exemplary method of manufacturing an IC card in accordance with the prior technology will be described with reference to FIGS. 14(a) to 14(c). As shown in FIG. 14(a) a thin IC chip 17 will be sucked from a pellet case 142 by means of a vacuum absorber 141. Then the picked up IC chip 17 will be transferred on an IC card substrate 15 (base film) having some adhesive paste applied thereon and pressed on it to fix thereon (see FIG. 14(b)). Thereafter the IC chip 17 attached will be covered by a covering sheet 19, as shown in FIG. 14(c).
Another example of attaching a semiconductor chip onto a base film is disclosed in the Japanese Patent Application Laid-Open No. Hei 08-316194. The method disclosed therein will be described with reference to FIGS. 2(a) to 2(c). In this example, as shown in FIG. 2(a), a plurality of semiconductor chips 17 having an antenna 16 is attached on a supporting sheet, these chips 17 will be pushed on a base film 15 having paste material 14 by means of a press head 21. Thereby the thin IC chips will be transferred and fixed on the film base as shown in FIG. 2(b). FIG. 2(c) is a cross-section indicating the chip and film encapsulated by an adhesive material 18 thereafter.
In the prior techniques as have been described above, the productivity is low because an IC chip is attached one at a time on a substrate. For example, in the method shown in FIGS. 14(a) to 14(c), the improvement of productivity will be limited because each chip is sucked and transferred one at a time. In the prior method shown in FIGS. 2(a) to 2(c), the press head is registered with each of chips to press one by one, the mechanism of assembly machine will become complex. In addition, a certain gap between two adjoining chips will be required during the transfer. This results in a difficulty of lowering the manufacturing cost.
In addition, if the thickness of IC chips to be delivered is for example equal to or less than 10 micrometers, the IC chip will be curled due to the internal stress of the semiconductor material. Thus, this may cause a damage in the chip, which will deform from a curled shape to a plane shape when sucked. In addition, since the chip is very thin, the sucking force of the vacuum sucker may result in a local deformation of the chip, leading to a change of device characteristics by the stress applied to the devices on the chip.